Grounding clamp with automatic disconnect



Sept. 30, 1969 A. MILO GROUNDING CLAMP WITH AUTOMATIC DISCONNECT Filed Feb. 14, 1968 v v 35 PIC-3.3 F1015 I INVE NTOR. I W m ATTORNEV United States Patent Ofiice 3,470,523 Patented Sept. 30, 1969 3,470,523 GROUNDING CLAMP WITH AUTOMATIC DISCONNEC'I August Milo, 1015 Schleifer Drive, Hillside, NJ. 07205 Filed Feb. 14, 1968, Ser. No. 705,337 Int. Cl. H01r 13/62 US. Cl. 33945 2 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a grounding clamp used for gasoline delivery vehicles, and the like. More specifically, it deals with a spring-loaded pliers type static grounding clamp attachable by cable to a convenient ground, and having pointed grounding contacts oppositely directed at each other and designed to bite into a conductive surface on the vehicle for good electrical contact. One novel feature of the conductive clamp is an automatic disconnect which enables the clamp to disconnect readily from the conductive surface of the vehicle in the event the truck driver forgets to disconnect the clamp. This feature comprises a holding means on one handle end of the clamp for holding, in electrical contact, the end of a wire rope or cable. Threading means is provided at the end of the other clamp handle through which said cable is loosely threaded, whereby said cable is enabled to be pulled through said means for opening said clamp jaws when said cable is pulled, so as to disengage said clamp from the conductive surface of the vehicle. A preferred threading means comprises a conductive rotatable pulley mounted on said clamp handle end over which the cable may travel during the disengaging operation.

Background of the invention The unloading of gasoline from trucks, for example, involves a safety problem due to possibility of build-up of static electricity.

This danger is, to a great part, avoided by the use of a grounding clamp which is attached by a cable to a ground at a truck terminal, bulk plant, or airport, for example. The pliers-type contacts of the clamp are attachable to a conductive surface of the vehicle (truck) before the gasoline is dispensed from the loading rack into the truck, or from tank truck to airport. Very often, the driver forgets to disconnect the clamp from the truck before driving away with the truck, and such action often causes damage to the vehicle, the cable, the ground or the clamp, or to all elements involved.

In Patent 1,520,485, one means proposed for avoiding this difliculty is by providing a conductive contact ball or rod which is conductively fastened to a ground, and onto which the spring clamp is slipped. However, the requirement of the special grounding means and the unsure spring contact therewith have been found satisfactory for use.

Patent 2,129,811 provides another type of ground connection, and is also subject to the same objections as already raised with respect to the previous patent.

There has been need for a clamp whose jaws are opened automatically during the disengaging operation, rather than having them forcibly pulled off.

Summary of the invention The present invention employs a conductive pliers-ilke clamp, wherein the spring-loaded jaws are provided with sharp biting contacts for biting into the conductive material of the vehicle. At the end of one handle grip, the end of a conductive wire or cable is anchored.

This cable then is threaded through an opening, or over a small pulley mounted on the end of the other handle grip. The other end of the cable is conductively attached to a convenient ground at the delivery point of the vehicle.

When the jaws are clamped onto a conductive surface of the vehicle, such as a metal plate, or any conductive part of the vehicle body, the vehicle is adequately grounded against discharge of static electricity. In the event the driver of the vehicle forgets to disconnect the clamp, and drives off in the vehicle, the pull on the cable first opens the jaws of the clamp and thus permits pulling away of the clamp without damage to the cable or vehicle body.

Brief description of drawing The invention will be more readily understood by reference to the accompanying drawing in which a preferred embodiment is described, and in which:

FIGURE 1 depicts an elevational side view of a clamp of the present invention, with cable attached.

FIGURE 2 presents a front elevational view thereof.

FIGURE 3 illustrates a rear elevational view thereof, with cable removed.

FIGURE 4 shows a cross-sectional front view taken along the plane of line 44 of FIGURE 1.

FIGURES 5 and 6 show alternative structures which would be seen as cross-sectional front views taken along the plane of line 5/65/6 in FIGURE 1.

The same numerals refer to similar parts in the various figures.

Description of the preferred embodiments Referring to the drawing, and particularly to FIG. 1, numeral 10 indicates generally a pliers-like clamp having jaws 11 and 12, and handle grips 13 and 14, respectively. Sleeve bearing portions 15 and 16 projecting from jaw 12 overlap inner bearing portions 17 and 18, respectively, and a hole 19 through all of these four portions enables insertion therein of pivot 20, serving as the fulcrum for the clamp. A spring 21 has its body turned around pivot 20, and its ends disposed in the channels of grips 13 and 14, and serves to force the grips outwardly causing jaws 1-1 and 12 to be forced towards each other. Ground contacts 22 and 23 have pointed ends 24 and 25 which abut each other. These contacts are preferably threaded to ride in threaded holes 26 and 27, in jaws 11 and 12, respectively, so that they may be adjusted, and lock nuts 28 and 29 serve to lock these in place.

The end of one grip 14 has a hole 30 into which may be inserted the end of cable 31 (the other end of the cable being conductively attached to a convenient ground at the delivery point). Screws 32 serve to anchor the cable end conductively to handle grip 14. Cable 31 is passed over pulley 33, made of bronze, or other conductive material. This pulley rides on shaft 34 which is fastened to the slide channel members of handle grip 13.

When in use, the handle is gripped to open jaws 11-12, and these jaws are allowed to close over a conductive plate of the vehicle or on any suitable part of the vehicle. Sharp, conductive points 2425 bite into the grounding plate of the vehicle and make a good contact.

In the event the driver of the vehicle forgets to remove clamp 10 from the vehicle to which it is attached, the pull of the vehicle on cable 31 (which may be made of stranded wire) will cause the clamp to open first against the action of spring 21. Thereafter, further movement of the vehicle will pull the opened clamp away from its attachment on the vehicle, thus avoiding damage to the vehicle, the clamp, or the cable in the event the points 24-25 were too firmly imbedded into the conductive material of the vehicle.

3 4 Although the pulley 33 is the preferred threading means threading means disposed on the end of the other handle for cable 31, it is also possible to employ other threading grip and through which said cable is threaded before means, such as the one shown in FIG. 5. In this case, it is led to a ground, whereby a pull of said vehicle cross piece 35 inserted between the channel side members on said cable will pull said cable through said threadof grip 13, is stationary, and cable 31 is designed to slide 5 ing means and open said clamp before pulling said over it. In FIG. 6, an eye 36 is attached to the end of clamp away. handle 13, and cable 31 is designed to slide through the 2. A grounding clamp according to claim 1, in which p g of Y said threading means comprises a pulley over which said 1 61mm! cable rides. 1. A grounding clamp for grounding a vehicle of the 10 References Cited type described comprising:

a pliers-type conductive body including a pair of pivoted UNITED STATES PATENTS handle grips connected to a pair of oppositely-dis- 3,183,469 5/1965 Tm ht b posed protruding jaws, and a spring designed to force said jaws together, MARVIN A. CHAMPION, Primary Examiner a pair of oppositely-disposed contact points attached to the inner portions of said jaws, in abutting relation, CLIFFORD Assistant Exammer V for gripping a grounding surface of said vehicle, US Cl XR anchoring means disposed at the end of one of said handle grips anchoring an end of a conductive cable 399-14, 255, 24-253 therein, and 

